Two patients in the same family with anti-ARS antibody-associated myositis

Abstract

Sir, We herein describe two familial cases of myositis and interstitial lung disease (ILD) in which both patients were serum anti-aminoacyl tRNA synthetase (anti-ARS) antibody positive. Case 1 (Mother): A 69-year-old female with a 3-month history of exertional dyspnea was suspected of having chronic hypersensitivity pneumonitis in August 2006. During the subsequent observation, her respiratory symptoms and chest high-resolution CT (HRCT) findings gradually worsened. There was no evidence of myositis when she was referred to our hospital in January 2008. Her serum creatine kinase (CK) level began to increase from September 2008, and she developed Raynaud's phenomenon and muscle weakness of the right arm. On admission in June 2009, her physical examination revealed fine inspiratory crackles in both lung bases and proximal muscle weakness. Arthritis and skin rash were absent. Laboratory data indicated elevated CK at 1513 IU/L (normal, 45–163 IU/L), C-reactive protein (CRP) at 1.25 mg/dl (normal, 0–0.3 mg/dl) and KL-6 at 1117 U/ml (normal, 0–499 U/L). Antinuclear antibody and anti-Jo-1 antibody were negative, but anti-EJ (glycyl-tRNA synthetase) antibody was detected by RNA immunoprecipitation using HeLa cell extracts as an antigen source. The electromyogram was typical for myositis; that is myotonic discharge in the iliopsoas and fibrillation in the deltoid and biceps. Her HRCT demonstrated ground-glass attenuation, reticulation and traction bronchiectasis predominantly in the lung bases (Figure 1). She was diagnosed with polymyositis (PM) accompanied by ILD and commenced on oral prednisolone (40 mg/day), which was ineffective for the ILD. She was readmitted in February 2010 because of progressive ILD and given pulse methylprednisolone at 1 g/day for 3 days, followed by combination therapy comprising oral prednisolone (50 mg/day) and cyclosporine (100 mg/day). Nevertheless, she required home oxygen therapy because of progressive respiratory failure.